import { Vector2 } from 'three';

let EdgeShader = {

    uniforms: {

        "tDiffuse": { value: null },
        "aspect": { value: new Vector2(512, 512) },
    },

    vertexShader: [

        "varying vec2 vUv;",

        "void main() {",

        "vUv = uv;",
        "gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",

        "}"

    ].join("\n"),

    fragmentShader: [

        "uniform sampler2D tDiffuse;",
        "varying vec2 vUv;",

        "uniform vec2 aspect;",

        "vec2 texel = vec2(1.0 / aspect.x, 1.0 / aspect.y);",


        "mat3 G[9];",

        // hard coded matrix values!!!! as suggested in https://github.com/neilmendoza/ofxPostProcessing/blob/master/src/EdgePass.cpp#L45

        "const mat3 g0 = mat3( 0.3535533845424652, 0, -0.3535533845424652, 0.5, 0, -0.5, 0.3535533845424652, 0, -0.3535533845424652 );",
        "const mat3 g1 = mat3( 0.3535533845424652, 0.5, 0.3535533845424652, 0, 0, 0, -0.3535533845424652, -0.5, -0.3535533845424652 );",
        "const mat3 g2 = mat3( 0, 0.3535533845424652, -0.5, -0.3535533845424652, 0, 0.3535533845424652, 0.5, -0.3535533845424652, 0 );",
        "const mat3 g3 = mat3( 0.5, -0.3535533845424652, 0, -0.3535533845424652, 0, 0.3535533845424652, 0, 0.3535533845424652, -0.5 );",
        "const mat3 g4 = mat3( 0, -0.5, 0, 0.5, 0, 0.5, 0, -0.5, 0 );",
        "const mat3 g5 = mat3( -0.5, 0, 0.5, 0, 0, 0, 0.5, 0, -0.5 );",
        "const mat3 g6 = mat3( 0.1666666716337204, -0.3333333432674408, 0.1666666716337204, -0.3333333432674408, 0.6666666865348816, -0.3333333432674408, 0.1666666716337204, -0.3333333432674408, 0.1666666716337204 );",
        "const mat3 g7 = mat3( -0.3333333432674408, 0.1666666716337204, -0.3333333432674408, 0.1666666716337204, 0.6666666865348816, 0.1666666716337204, -0.3333333432674408, 0.1666666716337204, -0.3333333432674408 );",
        "const mat3 g8 = mat3( 0.3333333432674408, 0.3333333432674408, 0.3333333432674408, 0.3333333432674408, 0.3333333432674408, 0.3333333432674408, 0.3333333432674408, 0.3333333432674408, 0.3333333432674408 );",

        "void main(void)",
        "{",

        "G[0] = g0,",
        "G[1] = g1,",
        "G[2] = g2,",
        "G[3] = g3,",
        "G[4] = g4,",
        "G[5] = g5,",
        "G[6] = g6,",
        "G[7] = g7,",
        "G[8] = g8;",

        "mat3 I;",
        "float cnv[9];",
        "vec3 sample;",

        /* fetch the 3x3 neighbourhood and use the RGB vector's length as intensity value */
        "for (float i=0.0; i<3.0; i++) {",
        "for (float j=0.0; j<3.0; j++) {",
        "sample = texture2D(tDiffuse, vUv + texel * vec2(i-1.0,j-1.0) ).rgb;",
        "I[int(i)][int(j)] = length(sample);",
        "}",
        "}",

        /* calculate the convolution values for all the masks */
        "for (int i=0; i<9; i++) {",
        "float dp3 = dot(G[i][0], I[0]) + dot(G[i][1], I[1]) + dot(G[i][2], I[2]);",
        "cnv[i] = dp3 * dp3;",
        "}",

        "float M = (cnv[0] + cnv[1]) + (cnv[2] + cnv[3]);",
        "float S = (cnv[4] + cnv[5]) + (cnv[6] + cnv[7]) + (cnv[8] + M);",

        "gl_FragColor = vec4(vec3(sqrt(M/S)), 1.0);",
        "}",

    ].join("\n")
};

export default EdgeShader;